The elucidation of mechanisms of secondary brain injury (the molecular and neurochemical events that occur following a traumatic impact) that contribute to the morbidity and mortality of victims of severe traumatic brain injury (TBI)can be accomplished through basic science investigations using animal models of TBI. In the past five years, we have reported species-specific differences in the type and contribution of these mechanisms to secondary injury. As a Brain Trauma Research Center focused on improving clinical outcomes following a TBI,we continue to examine the role of these mechanisms to human secondary brain injury. The Clinical Core will enable the investigators of the five primary projects to correlate the findings of their basic science investigations in animal models with mechanisms and therapeutics targeted at decreasing secondary brain injury in human victims of TBI by: 1) providing serum, cerebrospinal fluid, and dialysate samples obtained from microdialysis of the extracellular fluid, and brain tissue from human victims of severe TBI, 2) providing standardized care to these patients during their acute care hospitalization, 3) determining the functional status, neuropsychological outcomes, and psychosocial adjustment of these patients at 3, 6, 12 and 24 months after injury and,4) maintaining a comprehensive database that contains acute physiological and clinical data, as well as long term functional status, neuropsychological outcome and psychosocial adjustment data.